var data_zh = ['你知道吗', '六月', '一日', '星期一', '是', '儿童节'];
var data_en = ['do you know', 'June', 'One day', 'Monday', 'Yes', 'Children\'s day'];
var btn = document.querySelectorAll('.btn');

function fy(){
	for(var j = 0;j<data_en.length;j++){
		if(zhong.value == data_zh[j]){
			ying.value = data_en[j];demo();
		}else if(zhong.value == data_en[j]){
			ying.value = data_zh[j];demo();
		}
	}
}

function demo(){
	for(var i = 0;i<btn.length;i++){
		if(btn[i].className == 'leftz btn'){
			btn[i].className = 'btn'
		}else if(btn[i].className == 'btn'){
			btn[i].className = 'leftz btn'
		}
	}
}
